<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>

        /* 
            一个圆，设为红色
            中间在写一个圆，小一点，设为白色
            旁边的一个小把手，这里是用伪元素写的，可以用盒子，写一个长方形，定位上去
        */

        .box {
            font-size: 10em;
            /* This controls the size. */
            display: inline-block;
            width: 0.4em;
            height: 0.4em;
            border: 0.1em solid red;
            position: relative;
            border-radius: 0.35em;
        }

        .box::before {
            content: "";
            display: inline-block;
            position: absolute;
            right: -0.25em;
            bottom: -0.1em;
            border-width: 0;
            background: red;
            width: 0.35em;
            height: 0.08em;
            -webkit-transform: rotate(45deg);
            -moz-transform: rotate(45deg);
            -ms-transform: rotate(45deg);
            -o-transform: rotate(45deg);
        }
    </style>
</head>

<body>
    <div class="box"></div>
</body>

</html>